There are several processes known in the state of the art for tanning or treatment of leather. One which is relevant is putting several hides in a rotating drum filled with tanning bath and subjecting said hides to rotation. During rotation, the hides are soaked with tanning ingredients. After soaking, there is drying, using different processes, known in the art and not subject of the present invention hence unrelated to it.
European Patent EP 0 990 707 discloses a method for controlling the dosage cycle of chemicals, air and water in a fulling, tanning and dyeing drum, whereby, in a normal operating phase, the drum turns around its axis and air is circulated inside this drum by means of a blower, after being heated by the heating unit controlled by a thermostat connected to a relative humidity detector capable of signaling, should the humidity of the air inside the drum be less than a set rate. Further, this patent discloses a method whereby the water is sprayed in a mist by at least one nozzle.